In recent years, secondary batteries (also known as rechargeable batteries) have been widely used in various portable electric devices and electronic devices such as toys and handheld devices. This has imposed an increasingly high requirement on energy storage of secondary batteries. Lithium-ion secondary batteries have been increasingly used in such areas due to their advantages such as having a high energy, being capable of high-power discharge, and being environmentally friendly.
For normal operation, rechargeable batteries often have to cooperate with integrated circuit chips with other functions to achieve desirable operation effects. Usually, the rechargeable batteries are packaged separately from the integrated circuit chips and then connected with them for use in combination through circuit boards and wires. Such products include a large number of peripheral components, require many manufacture processes, and have a high cost. Also, the rechargeable batteries and integrated circuit chips have a large volume and a poor performance, which is not beneficial for the miniaturization.
In packaging a lithium ion secondary battery, each component of the lithium ion secondary battery occupies a relatively fixed space. The positive plate, the isolation diaphragm, and the negative plate are arranged inside the polymer battery cell, and the end of the positive plate facing away from the isolation diaphragm is packaged by a battery cell top seal of a predefined height. As the battery cell top seal occupies a certain height of the polymer battery cell, the usable space inside the polymer battery cell is reduced. The space utilization of a polymer battery cell is substantially related to the energy density and capacity of the lithium ion secondary battery. Generally, the larger the space utilization of the polymer battery cell is, the higher the energy density and capacity of the lithium ion secondary battery is. Therefore, existing lithium ion secondary batteries all suffer from the problems of a low energy density and capacity due to the low space utilization of the polymer battery cell.